workbench.action.terminal.deleteWordLeft Doesn't Work, Outputs ^W

[CoryOwens]

Issue Type: Bug

Steps to Reproduce:

1. Open the VS Code terminal (Ctrl+`, by default).
2. Type a command or a word into the terminal. (Ex: foo)
3. Press Ctrl+Backspace. (By default, Ctrl+Backspace is bound to workbench.action.terminal.deleteWordLeft when terminalFocus.)

Expected result: The word to the left of the cursor is deleted.

Actual result: The character ^W appears in the terminal input line.

This happens even if you change the shortcut. For instance, if you bind Alt+Backspace to workbench.action.terminal.deleteWordLeft, it will it too input ^W.

An older case (#19697) described the same (or at least similar) issue, but was closed as duplicated (#11314), even though the other case was specific to Mac.

VS Code version: Code 1.27.2 (f46c4c4, 2018-09-12T16:17:45.060Z)
OS version: Windows_NT x64 10.0.17134

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-6600U CPU @ 2.60GHz (4 x 2808)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: enabled video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled
Memory (System)	15.93GB (7.95GB free)
Process Argv	C:\Program Files\Microsoft VS Code\Code.exe
Screen Reader	no
VM	0%

Extensions (4)

Extension	Author (truncated)	Version
python	ms-	2018.8.0
cpptools	ms-	0.18.1
PowerShell	ms-	1.8.4
code-settings-sync	Sha	3.1.2

[Tyriar]

This is likely related to winpty, tracking in #45693